Grinding machine



Dec. 12, 1933. FR|T$H| 1,938,760

GRINDING MACHINE Filed Aug. 1'7, 1932 4 Sheets-Sheet l HIH I H 57 Gnome/3 Dec. 12, 1933. H. FRITSCHl GRINDING MACHINE Filed Aug. 17, 1932 4heets-Sheet 2 Dec. 12, 1933.

H. FRITSCHI GRINDING MACHINE Filed Aug. l7, 1932 4 Sheets-Sheet 3llllllllllllllllHHi m. 12, 1933. v H. mscm 1,938,760

GRINDING MACHINE Filed Aug. 17, 1932 4 Sheets-Sheet 4 WWW Patented Dec.12, 1933 UNITED STATES PATENT oFFlcE cinnati Grinders Incorporated,Cincinnati,

Ohio, a corporation of Ohio- Application August 17, 1932. Serial No.629,184i

19 Claims.

This invention relates to improvements in grinding machines andmore'especially to improvements in cross feed mechanism for effectingthe movement of the grinding wheel carriage.

An object of the invention is the provision of an improved hydraulicallyoperated cross feed mechanism.

Another object of the invention is the provision of a grinding machineincluding an hydraulically actuated cross feed mechanism that may beemployed in the performance of normal traverse grinding operation or forthe performance of what is known as plunge cutting operations.

A further object of the invention is the provision of improved crossfeed mechanism of the pick feed type and including an improved structurefor varying the amount of incremental feed.

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification considered inconjunction With the accompanying drawings, forming a part thereof, and,it is to be understood that any modifications may be made in the exactstructural details there shown and described within'the scope of theappended claims, without departing from or exceeding the spirit of theinvention.

In the drawings: a

Figure l is a front elevational view of a grinding machine embodying theimprovements of this invention.

Figure 2 is a fragmentary sectional'view taken on line 2-2 of Figure 1.v

Figure 3 is a fragmentary transverse sectional view through the machineas seen particularly from line 3-3 on Figure 1.

Figure 4 is a view partly in section and partly in elevation as seenfrom line 4-4 on Figure 3.

Figure 5 is a fragmentary sectional view taken on line 5--5 of Figure 1.I

Figure 6 is a sectional view taken on line 66 of Figure 2.

Figure 7 is a sectional view taken on line '7---'7 of Figure 6.

til

Figure 8 is a diagrammatic view illustrating the hydraulic circuitsinvolved in this invention.

Throughout the several views of the drawings similar referencecharacters are employed to denote the same or similar parts.

A machine embodying this invention may comprise a bed 10 of the usualconstruction as used with center type grinding machines and havingformed ,on its upper surface suitable guideways 11 and 12 receivingguide tongues depending from a work supporting table 13 mounted thereonfor movement relative thereto. The table 13 has ad-- justably secured toit, as is usual practice, a self-- contained head stock 14 and a tailstock 15 between which work pieces to be operated upon are disposed.

The table 13 and parts carried thereby may be translated relative to thebed by any suitable or desirable 'means, such for example, as that showndiagrammatically in Figure 8. The means shown in Figure 8 for effectingthe movement of the table 13 comprises a cylinder 16 carried by the bed10 and enclosing a double acting piston 17; Projecting from the piston17 is a piston rod 18 having its forward end secured to a bracket 19depending from the table 13 interiorly of the bed. In order to operatethe piston 17 there is provided a pump 20 having an inlet side to whichis connected a suction pipe 21 terminating in a suitable sump or-tank 22contain- .ing an hydraulic medium, preferably oil, utilized for theoperation of the piston 17. Connected with the discharge side of thepump 20 is a pipe or conduit 23 terminating on its upper end with avalve casing 24, shown structurally in Figure '7. Enclosed within thevalve casing 24 is a piston type slidable valve 25 having formed thereoncollars 26 and 27 between which is formed a cannelure 28. The cannelure28 is adapted to connect the discharge from the conduit or line 23 withone or the other of conduits 29 and 30 respectively terminating at theleft and right hand ends of the cylinder 16, as seen in Figure 8. Theconnection of the line 23 with one or the other of the conduits 29 and30 by the valve 25 automatically connects the remaining line through thevalve with one or the other of branch exhaust lines 31 and 32, which areconnected by a common return or exhaust line 33 that terminates in thesump 22. c

The valve 25 is adapted to be reversed at each end of the work tablestrokefor thereby reversing the movement of the table. For this purposethe table has secured to its forward surface a pair of reversing dogs11S and 119 adapted to engage with a projection 11'? extending from therear surface of a reversing lever 116, as is usual practice. This lever116 is keyed or otherwise secured to a shaft 120 rotatably journaled ina suitable bearing formed in a reversing plate 126 secured to theforward face of the bed 10 and the plate 126 carries and encloses thereversing mechanism including among other elements the reversing valve25 and the cross feed piston 69 and parts actuated thereby. Interiorlyof the plate 126 the shaft 120 has secured to its other end a lever 121which may be directly connected to the reversing valve stem, not shownin the drawings as this may be of any usual construction. Therefore,engagement of the reversing lever abutment 117 with either of thereversing dogs 118 or 1 19 will effect oscillation of the lever 116 andinitiate movement of the reversing valve 25.

In order to complete the movement of the reversing valve 25, and as isusual practice, there is provided a load and fire mechanism. This loadand fire mechanism comprises a valve stem 128 which passes through abore formed centrally through the valve 25 and to the stem 128 may bedirectly connected, as above described, the free end of the lever 121.The stem 128 is further provided with a collar 129 in which is formednotches 130 and 131 each having the walls inclined to act as camsurfaces. (lo-operating with the cam-like walls of the notches 130 and131 is a yieldably actuated load and fire mechanism comprising a member132 having a head whose surfaces are inclined to engage the cam faces ofnotches 130 and 131. The member 132 has a counterbore therein receivinga spring 133 which abuts on one end with thebase of the counterbore andon the other end with a plug 134 that closes the passage 135 throughwhich the projection on the reversing lever for oscillating same, whichin turn oscillates the lever 121 for shifting the valve stem 128. Themovement of the valve stem 128 causes the notches 130 and 131 to bemoved relative to the member 132 and due to the inclined walls of thenotches causes said member 132 to ride up the side of the notch in whichit is positioned. By the time the member 132 reaches the top of theridge between the notches, the lost motion between the valve 25 and thecollar 129 or shoulder 136 is taken up and as soon as the member 132passes said ridge the spring, which was compressed during the upwardmovement of the member 132, expands or fires the valve stem 128 to theother end of its movement carrying with it the valve 25 and therebyreversing the connection through said valve.

The bed 10 has extending from its rear side an extension 34 on the uppersurface of which is formed guideways 35 for a slide or carriage 36. Thecarriage 36 rotatably supports a spindle 3'7 to the end of which issecured a grinding wheel 38 for operation on the work carried by thehead and tail stocks. The grinding wheel 38 is suitably enclosed withina guard 39 that confines the coolant usual with grinding machines.

The carriage 36 is adapted to be actuated relative to the bed extension34 toward the work to effect a stock-removal therefrom and from the workto permit a replacement of the work. For this purpose the carriage 36has secured to it or'formed integral therewith and depending interiorlyof the bed extension 34 a bracket 40 having keyed or pinned therein anut 41. The nut 41 is in threaded engagement with a cross feed screw 42and the nut has extending from it a cylindrical skirt or guard 43adapted toprotect the threads of the screw from dirt and other foreignsubstances. The screw 42 is adapted to be both axially shifted androtatably actuated for effecting the movement of the carriage, theformer movement being employed for rapidly adjusting the position to thecarriage and grinding wheel and the latter for finely positioning saidcarriage and for incrementally feeding the work and wheel relative toone another.

To efiect the rapid movement of the carriage 36 the screw has secured toit near its outer end a piston 44 enclosed within a cylinder 45 whichhas its ends closed as by means of heads 46 and 47. These heads 46 and4''! have extending through them the screw 42 for forming bearings forsaid screw. Respectively secured to the heads 46 and 47 are pipes 48 and49 which convey hydraulic medium to opposite sides of the piston 44 foreffecting its movement. These pipes are connected with a suitable sourceof hydraulic pressure and with the sump, which will take place through areversing valve similar to the valve 25.

The cylinder 45 and parts associated therewith are secured to anextension 50 projecting rearwardly from a plate or housing 51 secured tothe forward face of the bed 10. Enclosed within the housing 51 andjournaled in the extension 50 is a gear 52 having a bore centrallythereof in which is formed a plurality of keyways receiving the splinedportion 53 of the screw 42. By this construction it will be noted thatthe screw may be axially shifted without breaking the driving connectionbetween the splined portion 53 and the hub of the gear 52. Meshing withthe gear 52 is a pinion 54 formed integral with or secured to a shaft 55rotatably journaled insuitable antifriction bearings carried by thehousing 51 and housing cover plate 56. The shaft 55 has looselyjournaled on it'a hand wheel 5'? carrying a slidable handle or plunger58. The plunger 58 has interiorly thereof a spring 59 tending toyieldably shift a projecting pin or tongue 60 thereof into any oneof aplurality of sockets 61 formed around the ratchet wheel 62. The ratchet62 is provided exteriorly with ratchet teeth 63 and interiorly withgear'teeth 64. The gear teeth 64 mesh with the teeth of a gear 65rotatably journaled on a stud 66carried by a plate member 67 keyed orotherwise secured to the shaft 55. The gear 65 in turn meshes with apinion 68 formed integral with the hand wheel 57 or at least secured tosaid hand wheel 57 for movement with said hand wheel.

With the parts in the position shown in Figure 3, the rotation of thehand wheel 57, by means of the plunger handle 58, and theinterengagement of the pin 60 and ratchet wheel 62, effects a unitaryrotation of the parts and the shaft 55 at the same rate. r The rotationof the shaft 55 rotates the pinion 54 and gear 52 which through itsconnection with the screw 42 effects the rotation thereof and consequentadjustment of the slide. In order to rotate the screw 42 at a very slowrate of speed, as when adjusting the parts to take up for wheel wear,which is in the nature of a fraction of a thousandth of an inch, theplunger handle 58 is withdrawn against the spring 59 to withdraw the pin60 from its socket 61 whereupon the hand wheel is again rotated, butthis time only turns the pinion 63 associated therewith which throughthe planetary gear 65 and internal gear 64 rotates the plate 67 and veryslowly rotates the screw. By this construction the screw is rotated buta fraction of a revolution for each complete revolution of the handwheel 57 and thereby incrementally adjusts the position of the partswhile with the plunger pin 60 in engagement with one of its sockets sothat the parts are given a unitary movement, the adjusting screw isgiven a complete revolution for each rotation of the hand wheel.

In the normal operation of the machine these parts are automaticallyoperated as by means of a pawl mechanism operating on the teeth 63 ofthe ratchet 62. This pawl mechanism comprises a piston 69 enclosedwithin a cylinder '70 formed, for example as shown in Figure '7,integral with the valve casing 24. The piston 69 has projecting from itsends reduced nipples 71 and '72 adapted to engage with plugs '73 and 74carried by the ends of the cylinder '70. The nipples '71 and '72 at alltimesspace the end of the piston 69 from the plugs '73 and '74 for atall times maintaining a chamber at the ends of the cylinder incommunication with the pressure and exhaust conduits utilized foroperating said piston. As shown in Figure 8, the right and left handends of the cylinder '70 are respectively connected by means of conduits'75 and '76 with the conduits 29 and 30. The piston 69 is provided onone side with rack teeth '77 meshing with the teeth '78 formed on thelower end of a vertically oscillatable shaft '79. The verticallyoscillatable shaft 79 is mounted for movement in the block 79a in whichis formed the valve casing 24 and cylinder '70 and projects above theupper surface of saidblock.

A heart-shaped cam member 80 is secured to or formed integral with themember '79 above the block and is adapted to engage a roller 81rotatably carried by the under surface of a lever 82.

The lever 82 is pivoted at 83 to the upper surface of the block 79a andextends forwardly through an opening 84 formed in the housing coverplate 56, as well as through an opening 85 formed in the adjacent sideof a substantially cylindrical housing 86. The free end 8'7 of the lever82 is disposed interiorly of the housing 86 and is adapted whenoscillated to contact with the end of a plunger 88 for shifting same.This plunger 88, see Figure 4, is provided with an enlarged portion 89at its rear end followed by a reduced portion 90 to which is connected ahead 91. The head 91 is provided with a longitudinal slot 92 in which isdisposed a pawl 93 having its rear end pivoted as at 94. The free end ofthe pawl 93 is provided with a nose or point 95 which is adapted toengage behind the ratchet teeth 63. The pawl 93 is further provided witha socket 96 in which is a spring 97 abutting on opposite ends with thebase of the socket 96 and with the base of the notch 92.

The plunger 88 and parts carried thereby are received in a sleeve 98axially adjustable relative to the housing 86. The sleeve is providedwith a bore 99 of a diameter equal tothe enlarged end portion 89 of theplunger and provides a guide for the movement of the plunger 88.Surrounding the reduced portion 90 of the plunger is a spring 100 whichabuts on one end with the shoulder formed'by the enlarged portion 89 ofthe plunger and on the other end with a radial flange 100a forming thebase of the bore 99 and the base of a counterbore on the other sidethereof. The spring 100 yieldably urges the plunger 88 to the left, asseen in Figure 4, and thereby maintains contact between the end of theplunger head 91 and the radial flange 100a forming the base of acounterbore in the sleevein which said head is disposed.

For each axial reciprocation of the plunger 88 the pawl 93 is adapted toengage one or more of the ratchet teeth 63. For the purpose of'determining the amount or number of ratchet teeth to be engaged. foreach reciprocation of the plunger 88, the sleeve 98 is axiallyadjustable and adapted to be held in its adjusted positions. For thispurpose the upper surface of the sleeve at one end thereof is providedwith rack teeth 101 adapted to engage with the teeth on rack pinion 102keyed or otherwise secured to a shaft 103 for movement therewith. Theunder surface of the sleeve is provided with notches 104 co-operatingwith the spring pressed detent 105. This detent is counterbored toreceive the spring 106 which abuts on opposite ends with the base of thecounterbore and a plug 107 which closes the passage 108 in which thespring is disposed. The sleeve 98 is formed at the end of thecounterbore in which the plunger head 91 is disposed with a bevelled orcammed face 109 co-operating with the inclined or cammed surface 110formed on the pawl 93 adjacent its nose 95 for actuating the pawl in adirection against the yielding resistance of the spring 96.

From the foregoing it will be noted that the lever 82 has a definitepath of oscillation imparted thereto by the cam 80 and that the free endof the plunger enlarged portion 89 is variably spaced relative to thepath of oscillation of the free end 87 of the lever 82. From this itwill be seen that the plunger 88 is shifted relative to its sleeve 98variable amounts depending upon the axial position thereof relative tothe housing 86 for thereby variably effecting incremental feedingmovements of the grinding wheel and its car- 'riage toward the work.

In order to rotate the shaft 103 and thereby the pinion for shifting thesleeve 98, the shaft 103 is journaled in the housing 86 projectingbeyond said housing toward the operator. The projecting end of the shaft103 has secured to it a lever 111 carrying a locking pawl 112 adapted toenter suitable notches 113 formed on a plate carried by the housing 86.The pawl 112 is yieldably urged toward its locking plate by means of aspring 114 which surrounds the stem of the pawl. The pawl stem hasscrewed to its free end a knob 115 whereby the pawl is actuated againstthe resistance of the spring 114 for releasing the lock to permitfurther adjustment of the handle 111.

It will be noted from Figure 8 that the same valve 25 that is utilizedfor effecting the reverse coupling of the hydraulic medium with thecylinder 16 is utilized for effecting the reverse operation of thepiston 69. From this it will be seen that for each reversal of the tablemovement the piston 69 is operated for effecting an incremental feed ofthe grinding wheel toward the work. The reverse shifting of the valve 25is effected by the means described above through the operation of thereversing dogs 118 and 119 acting on the lever 116. The above describedstructure is utilized during normal traverse grinding, that is, when thework table is translated to traverse the work across the grinding wheelwhen it is desired that the table tarry slightly before reversal. When,however, it is desired to perform a plunge cutting operation, that is,with substantially no table traverse except a slight axial movementbetween the work and wheel to break up grinding linesQit is desired thata substantially instantaneous reverse of the table be had and within anextremely short table stroke. For this reason, and as shown in Figure'7, the lever 121 is pivoted at 122 to one end of a link 123 which hasits other end pivoted 125. This lever 125 is in turn pivoted at itsupper 'at 124 to a point intermediate a depending lever end to theinterior'of the reverse" plate or housing 126 and has its lower endpivoted at 127 to the stem of the reversing valvef25.

Due to the particular lever and linkage arrangement, namely the lever121, link 123 and lever 125, the valve stem 128 has imparted to itconsiderably more movement than the lever 121. By this construction thevalve 25 may be operated from its reverse positions with a very shortmovement of the lever 121 and consequently the lever 116. In otherwords, with this construction the table 13 may be reciprocated throughan extremely short stroke and therefore at a comparatively rapid ratefor breaking up grinding lines on the work, as when performing plungecutting operations. By this construction also and since the reversingvalve 25 effects the incremental infeed of the grinding wheel for eachreversal of the valve the grinding wheel is fed into the work, therebyexpeditiously performing plunge cutting operations on work pieces withina minimum of time and without the use of special mechanism as was thecase with grinding machines of the past that were adapted to per- =formboth traverse grinding and plunge cutting operations on the samemachine.

What is claimed is:

1. In a cross feed mechanism for use with grinding machines thecombination with a bed, of

a grinding wheel carriage mounted thereon for movement relativethereto,an adjusting screw operatively connected with the carriage, and aratchet and pawl mechanism for incrementally rotating the screw andthereby incrementally feeding the carriage relative to the bed includinga reciprocable plunger having secured thereto the pawl, a sleeveenclosing the plunger, a spring yieldably shifting the plunger in onedirection relative to the sleeve, means associated with the plunger andsleeve for limiting the movement of the plunger under influence of thespring, and hydraulically actuated means for shifting the plungeragainst the resistance of the spring.

2. In a cross feed mechanism for use with grinding machines thecombination with a bed, of a grinding wheel carriage mounted thereon formovement relative thereto, an adjusting screw operatively connected withthe carriage, and a ratchet and pawl mechanism for incrementallyrotating the screw and thereby incrementally feeding the carriagerelative to the bed including a reciprocable plunger having securedthereto the pawl, a sleeve enclosing the plunger, a spring yieldablyshifting the plunger in one direction relative to the sleeve, meansassociated with the plunger and sleeve for limiting the movement of theplunger under influence of the spring, an oscillatable lever adapted tohave its free end engaging with the plunger to shift same against theresistance of the spring, and hydraulic means for effecting theoscillation of the lever.

3. In a cross feed mechanism for use with grinding machines thecombination with a bed, of a grinding wheel carriage mounted thereon for'movement relative thereto, an adjusting screw operatively connectedwith the carriage, and a ratchet and pawl mechanism for incrementallyrotating the screw and thereby incrementally feeding the carriagerelative to the bed including a reciprocable plunger having securedthereto the pawl, a sleeve enclosing the plunger, a spring yieldablyshifting the plunger in one direction relative to the sleeve, meansassociated with the plunger and sleeve for limiting the movement of theplunger under influence of the spring, an oscillatable lever adapted tohave its free end engaging with the plunger to shift same against theresistance of the spring, an oscillatable shaft, a cam on said shaft, anoperative coupling be-- tween the cam and lever whereby oscillations ofthe cam effect oscillations of the lever, and an hydraulically actuatedpiston for oscillating the shaft.

4. In a cross feed mechanism for grinding machines the combination witha bed, a grinding wheel carriage mounted thereon for movement relativethereto, of a screw operatively associated with the carriage, a ratchetand pawl mechanism for effecting incremental rotation of the screwincluding a reciprocable plunger to which is pivotally secured the pawl,yieldable means for shifting the plunger in one direction, power meansfor shifting the plunger in the other. direction, and means for variablypositioning the plunger relative to the power shifting means whereby tovary the stroke of the plunger and consequent feeding of the screw perreciprocation of the plunger, comprising a sleeve enclosing the plunger,a housing supporting the sleeve, co-opcrating means on the sleeve andplunger for limiting the movement of the plunger under the influence ofthe yielding means, and means shifting the sleeve relative to itshousing.

5. In a cross feed mechanism for grinding machines the combination witha bed and a grinding wheel carriage mounted thereon for movementrelative thereto, of a screw operatively associated with the carriage, aratchet and pawl mechanism for effecting incremental rotation of thescrew including a reciprocable plunger to which is pivotally secured thepawl, yieldable means for shifting the plunger in one direction, powermeans for shifting the plunger in the other direction, and means forvariably positioning the plunger relative to the power shifting meanswhereby to vary the stroke of the plunger and consequent feeding of thescrew per reciprocation of the plunger, comprising a sleeve enclosingthe plunger, a housing supporting the sleeve, co-operating means on 120the sleeve and plunger for limiting the movement of the plunger underthe influence of the yielding means, said sleeve having a rack securedthereto, a pinion engaging the rack, and a spring detent for holding thesleeve in its relative posi- 125 tions relative to the housing.

6. In a cross feed mechanism for use with grinding machines and thelikethe combination with a ratchet and pawl mechanism for effecting saidcross feed, of a'reciprocable plunger, a head 130 on said plunger towhich the pawl is pivotally secured, a sleeve enclosing the plunger andhaving a radialflange intermediate its ends, yielding means for shiftingthe plunger relative to the sleeve and engaging the plunger head withthe 135 radial flange, the sleeve having a cam face formed at one endthereof co-operating with a cam on the pawl for disengaging the pawlfrom the ratchet when in its normal retracted position under influenceof the spring, and power means 140 for shifting the plunger relative tothe sleeve to disengage the pawl cam and sleeve cam and effect"engagement between the pawl and ratchet teeth.

means for shifting the plunger relative to the sleeve and engaging theplunger head with the radial flange, the sleeve having a cam face formedat one end thereof co-operating with a cam on the pawl for disengagingthe pawl from the ratchet when in its normal retracted position underinfluence of the spring, power means for shifting the plunger relativeto the sleeve to disengage the pawl cam and sleeve cam and effectengagement between the pawl and ratchet teeth, a housing enclosing thesleeve, means for shifting the sleeve relative to the housing to therebyvary the effect of the power operating means and vary the amount ofrotation of the ratchet per stroke of the plunger, and means for lockingthe sleeve in its adjusted position relative to the housing.

8. In a grinding machine of the class described the combination of abed, a work supporting table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for incrementalmovement toward the work supporting table, hydraulic means for effectinga reverse translation of the table, a ratchet and pawl mechanism foreffecting the incremental feed of the grinding wheel carriage andincluding a reciprocable plunger carrying the pawl, 'a reverselyoscillatable cam for effecting the shifting of the plunger on eachoscillation thereof, an hydraulically actuated piston for oscillatingthe cam, and a reversing valve operable by the table at each end of itstranslatory stroke for reversing the movement of the table and effectingthe oscillation of the cam.

9. In a grinding machine of the class described the combination of abed, a work supporting table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for incrementalmovement toward the work supporting table, hydraulic means for effectinga reverse translation of the table, a ratchet and pawl mechanism foreffecting the incremental feed of the grinding wheel carriage andincluding a reciprocable plunger carrying the pawl, a reverselyoscillatable cam for effecting the shifting of the plunger on eachoscillation thereof, an hydraulically actuated piston for oscillatingthe cam, a

reversing valve operable by the table at each end of its translatorystroke for reversing the movement of the table and effecting theoscillation of the cam, and yielding means for retracting the plunger.

10. In a grinding machine of the class described the combination of abed, a work supporting table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for incrementalmovement toward the work supporting table, hydraulic means for effectinga reverse translation of the table, a ratchet and pawl mechanism foreffecting the incremental feed of the grinding wheel carriage andincluding a reciprocable plunger carrying the pawl, an hydraulicallyactuated piston for shifting the plunger, a reversing valve operable bythe table at each end of its translatory stroke for reversing themovement of the table and the operation of the plunger in one direction,yielding means for retracting the plunger, and cam means for disengagingthe ratchet and pawl when the plunger is in a retracted position.

11. In a mechanism of the class described the combination with a bed, ofa work supporting table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for movementtoward the work supporting table, hydraulic means for effecting thetranslation of the table and feed of the grinding wheel carriage, areversing valve for reversing the direction of movement of the table ateach end of its stroke in a given direction, a reversing lever operableby the table for effecting the reversing of the reverse valve and meansbetween the reversing lever and reversing valve whereby the movementimpartcdto the reversing lever is amplified for shifting the valve andwhereby the amount of table movement per reversal is reduced to aminimum.

12. In a mechanism of the class described the combination with a bed, ofa work supporting table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for movementtoward the work supporting table, hydraulic means for effecting thetranslation of the table and feed of the grinding wheel carriage, areversing valve for reversing the direction of movement of the table ateach end of its stroke in a given direction, a reversing lever operableby the table for effecting the reversing of the reverse valve, meansbetween the reversing lever and reversing valve whereby the movementimparted to the reversing lever is amplified for shifting the valve andwhereby the amount of table movement per reversal is reduced to aminimum, and connections between the hydraulic cross feed mechanism andthe table translating 1';

mechanism whereby the grinding wheel carriage is incrementally fed foreach reversal of table translation.

13. In a mechanism of the class described the combination with a bed, ofa work supporting '1 table mounted thereon for translation relativethereto, a grinding wheel carriage mounted on the bed for movementtoward the work supporting table, hydraulic means for effecting thetranslation of the table and feed of the grinding wheel carriage, areversing valve for reversing the direction of movement of the table ateach end of its stroke in a given direction, a reversing lever operableby the table for efiecting the reversing of the reverse valve, meansbetween the reversing lever and reversing valve whereby the movementimparted to the reversing lever is amplified for shifting the valve andwhereby the amount of table movement per reversal is reduced to aminimum, connections between the hydraulic cross feed mechanism and thetable translating mechanism whereby the grinding wheel carirage isincrementally fed for each reversal of table translation, and a commonpressure source for actuating the table translating mechanism andgrinding wheel carriage feeding mechanism. 7

14. In a grinding machine of the class described the combination with abed, a work supporting table mounted thereon for translation relativethereto, and a grinding wheel carriage mounted on the bed for movementtoward the work supporting table, of cross feed mechanism for effectingthe incremental movement of the carriage toward the table including aratchet and pawl mechanism, a plunger to which the pawl is pivotallysecured, a reversely oscillatable cam, and a vpivotally mounted leverhaving contact with the cam intermediate its ends and whereby the saidlever is oscillated about its pivotal mounting, said lever having itsfree end in line with the plunger for engagement therewith and effectinga movement thereof upon oscillation of the lever.

15. In a grinding machine of the class de-- scribed the combination witha bed, a work supthe plunger.

porting table mountedthereon for translation relative thereto, and agrinding wheel carriage carried by the bed for movement toward the worksupporting table, of a cross feed mechanism for effecting themovement/0f the carriage including a ratchet and pawl, a plungerpivotally carrying the pawl, a reversely oscillatable cam, a leverpivotally mounted at one end and engaging the plunger at the other endand contacting with the cam intermediate its ends, and means foreffecting the reverse oscillations of the cam for oscillating the leverin one direction and correspondingly reciprocating the plunger.

16. In a grinding machine of the class described the combination with abed, a work supporting table mounted thereon for translation relativethereto, and a grinding wheel carriage carried by the bed for movementtoward the work supporting table, of a cross feed mechanism forefiecting the movement of the carriage including a ratchet and pawl, aplunger pivotally carrying the pawl, a reversely oscillatable cam, alever pivotally mounted at one end and engaging the plunger at the otherend and contacting with the cam intermediate its ends, means forefiecting the reverse oscillations of the cam for oscillating the leverin one direction and correspondingly reciprocating the plunger, andyielding means for shifting the plunger in the opposite direction andreturning the lever to its normal position.

17. In a grinding machine of the class described the combination with abed, a work supporting table mounted thereon for translation relativethereto, and a grinding wheel carriage carried by the bed for movementtoward the work supporting table, of a cross feed mechanism foreffecting the movement of the carriage including a ratchet and pawl, aplunger pivotally-carrying the pawl, a reversely oscillatable cam, alever pivotally mounted at one end and engaging the plunger at the otherend and contacting with the cam intermediate its ends, means foreffecting the reverse oscillations of the cam for oscillating the leverin one direction and correspondingly reciprocating the plunger, yieldingmeans for shifting the plunger in the opposite direction and returningthe lever to its normal position, and means for varying the position ofthe plunger with respect to the lever, thereby providing lost motionbetween the plungerand lever so that equal oscillations of the cam andlever efiect variable length of reciprocations of 18. Ina grindingmachine of the class described the combination with a bed, a worksupporting table mounted thereon for translation relative thereto, and agrinding wheel carriage carried by the bed for movement toward the worksupporting table, of a cross feed mechanism for effecting the movementof the carriage including a ratchet and pawl, a plunger pivotallycarrying the pawl, a reversely oscillatable cam, a lever pivotallymounted at one end and engaging the plunger at the other end andcontacting with the cam intermediate its ends, means for effecting thereverse oscillations of the cam for oscillating the lever in onedirection and correspondingly reciprocating the plunger, yielding meansfor shifting the plunger in the opposite direction and returning thelever-to its normal position, means for varying the position of theplunger with respect to the lever, thereby providing lost motion betweenthe plunger and lever so that equal oscillations of the cam and levereffect variable length of reciprocations of the plunger, and hydraulicactuable means for effecting the reverse oscillations of the cam.

19. In a grinding machine of the class described the combination with abed, a work supporting table mounted thereon for translation relativethereto, and a grinding wheel carriage carried by the bed for movementtoward thework supporting table, of a cross feed mechanism for effectingthe movement of the carriage including a ratchet and pawl, a plungerpivotally carrying the pawl, a reversely oscillatable cam, a leverpivotally mounted at one'end' and engaging the plunger at the other endand contacting with the cam intermediate its ends, means for effectingthe reverse oscillations .of the cam for oscillating ,3 the lever in onedirection and correspondingly reciprocating the plunger, yielding meansfor shifting the plunger in the opposite direction and returning thelever toits normal position, means for varying the position of theplunger with re- 5. spect to the lever, thereby providing lost motionbetweenthe plunger and lever so that equal oscillations of the cam andlever effect variable length of reciprocations of the plunger, hydraulicactuable means for effecting the reverse oscillationsof the cam,hydraulic means for translating the work supporting table, a connectionbetween the work supporting table translating means'and the camoscillating means whereby the said hydraulic means are simultaneouslyactuated, and a reversing valve operable by the table for simultaneouslyreversing the operation of the hydraulic means.

HANS FRITSCHI.

